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docs/session_summaries/2026-01-28-documentation-update-relative-rendering.md

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+# 2026-01-28 - Documentation Update for Relative Rendering
+
+## Changes Made
+
+Updated rendering documentation to accurately reflect the actual implementation of the relative rendering system. The original planning document (`docs/planning/local_rendering_frame.md`) described a dual-frame local rendering system that was not implemented. The actual solution was simpler: relative rendering with linear scaling and child indicators.
+
+## Commits
+
+1. `2b68e2e` - Update rendering documentation to reflect relative rendering implementation
+
+## Documentation Updates
+
+### `docs/rendering.md` (+46 lines, updated)
+
+**Updated sections:**
+- **Overview**: Changed from "logarithmic distance scaling" to "linear distance scaling, relative rendering with child indicators"
+- **RenderState struct**: 
+  - Removed: `previous_selected_body`, `was_following_body`
+  - Added: `last_target_index`, `camera_target_enabled`
+- **Scaling Factors**: 
+  - Changed from logarithmic scaling with separate size scale (0.02)
+  - To linear scaling with unified distance/size scale (1e-9 for both)
+  - Removed `scale_radius()` log10 formula
+- **Camera System**: Added documentation for `get_initial_camera_distance()` function
+- **Child Indicators**: New section added:
+  - NASA Eyes-style hollow circles (20px radius, 2px thickness)
+  - Text label centered inside
+  - White for bodies, cyan for spacecraft
+  - Only shown when body selected
+  - Uses `GetWorldToScreen()` after `EndMode3D()`
+- **Relative Rendering**: New section added:
+  - Body selected: body at origin, children relative, full float precision
+  - Spacecraft selected: parent relative to spacecraft, no siblings
+  - Benefits: improved visibility, better precision, auto camera positioning
+- **Render Order**: Added child indicators at position 6
+- **Module Functions**: Added `get_initial_camera_distance()` to Camera section
+- **TODO Items**: Added 2 items from planning doc:
+  1. Distant Bodies (indicators for non-children)
+  2. Smooth Frame Transitions (interpolation)
+
+### `docs/planning/local_rendering_frame.md` (deleted, -596 lines)
+
+Removed the original planning document as it described an unimplemented dual-frame system. Relevant TODO items were preserved in rendering.md.
+
+## Net Line Count
+
+**Total changes: +46, -610 lines**
+
+## Remaining Issues
+
+None. Documentation now accurately reflects the actual implementation.
+
+## Next Steps
+
+Ready to merge `render-fix` branch back to `main`.
+
+## Technical Reference Update
+
+The `docs/technical_reference.md` file does not need updates - it correctly references `docs/rendering.md` for complete rendering documentation and does not contain conflicting information.